U.S. patent number 8,739,549 [Application Number 12/755,369] was granted by the patent office on 2014-06-03 for systems and methods for feedstock injection.
This patent grant is currently assigned to General Electric Company. The grantee listed for this patent is Benjamin Campbell Steinhaus. Invention is credited to Benjamin Campbell Steinhaus.
United States Patent |
8,739,549 |
Steinhaus |
June 3, 2014 |
Systems and methods for feedstock injection
Abstract
Systems and methods for injection of feedstock are included. In
one embodiment, a system includes a solid fuel injector. The solid
fuel injector includes a solid fuel passage, a first gas passage,
and a second gas passage. The solid fuel passage is configured to
inject a solid fuel through a fuel outlet in a fuel direction. The
first gas passage is configured to inject a first gas through a
first gas outlet in a first gas direction. The second gas passage
is configured to inject a second gas through a second gas outlet in
a second gas direction. The first gas direction is oriented at a
first angle relative to the fuel direction. The second gas
direction is oriented at a second angle relative to the fuel
direction, and the first and second angles are different from one
another.
Inventors: |
Steinhaus; Benjamin Campbell
(Missouri City, TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Steinhaus; Benjamin Campbell |
Missouri City |
TX |
US |
|
|
Assignee: |
General Electric Company
(Schenectady, NY)
|
Family
ID: |
44585545 |
Appl.
No.: |
12/755,369 |
Filed: |
April 6, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110239658 A1 |
Oct 6, 2011 |
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Current U.S.
Class: |
60/772;
60/781 |
Current CPC
Class: |
F23D
1/00 (20130101); F23N 1/02 (20130101) |
Current International
Class: |
F02C
1/00 (20060101) |
Field of
Search: |
;60/39.281,39.465,740,742,746,781,772 ;239/416.5,422,422.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0421820 |
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Apr 1991 |
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EP |
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2113717 |
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Nov 2009 |
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EP |
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2427261 |
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Dec 2006 |
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GB |
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2006/078543 |
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Jul 2006 |
|
WO |
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2009/134530 |
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Nov 2009 |
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WO |
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Other References
PCT Search Report issued in connection with corresponding WO Patent
Application No. US2011/028334 filed on Mar. 14, 2011. cited by
applicant.
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Primary Examiner: Wongwian; Phutthiwat
Attorney, Agent or Firm: Fletcher Yoder P.C.
Claims
The invention claimed is:
1. A system, comprising: a solid fuel injector, comprising: a solid
fuel passage disposed axially with respect to the solid fuel
injector and configured to inject a solid fuel through a fuel
outlet in a fuel direction; and a first gas passage configured to
inject a first gas through a first gas outlet in a first gas
direction, wherein the first gas direction is oriented at a first
angle relative to the fuel direction; a second gas passage
configured to inject a second gas through a second gas outlet in a
second gas direction, wherein the second gas direction is oriented
at a second angle relative to the fuel direction, and the first and
second angles are different from one another, wherein the first gas
passage is disposed concentrically surrounding the solid fuel
passage, and the second gas passage is disposed concentrically
surrounding the first gas passage; a fuel pump fluidly coupled to
the solid fuel passage and communicatively coupled to a controller,
wherein the fuel pump is configured to direct the solid fuel into
the solid fuel passage; a first valve fluidly coupled to the first
gas passage and communicatively coupled to the controller, wherein
the first valve is configured to adjust a first flow of the first
gas through the first passage; and a second valve fluidly coupled
to the second gas passage and communicatively coupled to the
controller, wherein the second valve is configured to adjust a
second flow of the second gas through the second passage; and the
controller configured to inject the solid fuel axially with respect
to the solid fuel injector by actuating the fuel pump, inject the
first gas concentrically about the solid fuel passage to impact the
solid fuel by actuating the first valve, and inject the second gas
concentrically about the first gas passage to impact the first gas,
the solid fuel, or a combination thereof, by actuating the second
valve.
2. The system of claim 1, wherein the controller is configured to
adjust a first gas flow rate of the first gas by adjusting the
first valve and a second gas flow rate of the second gas by
adjusting the second valve.
3. The system of claim 2, wherein the controller is configured to
adjust a ratio between the first and second gas flow rates to
adjust a spray angle of the solid fuel by adjusting the first
valve, the second valve, or a combination thereof.
4. The system of claim 2, wherein the controller is configured to
adjust a fuel flow rate of the solid fuel relative to the first gas
flow rate, the second gas flow rate, or a combination thereof, by
adjusting the fuel pump.
5. The system of claim 4, wherein the controller is configured to
adjust the fuel flow rate, the first gas flow rate, or the second
gas flow rate, in response to feedback from a combustion
chamber.
6. The system of claim 5, wherein the feedback comprises gasifier
feedback from the combustion chamber of a gasifier.
7. The system of claim 6, comprising the gasifier coupled to the
solid fuel injector.
8. The system of claim 1, wherein the first gas passage is a first
annular passage, and the second gas passage is a second annular
passage.
9. The system of claim 1, wherein the fuel outlet, the first gas
outlet, and the second gas outlet are disposed in a common
plane.
10. The system of claim 1, wherein the solid fuel passage is a coal
passage, the first gas passage is a first oxygen passage, and the
second gas passage is a second oxygen passage.
11. A system, comprising: a solid fuel injection controller
configured to control a solid fuel flow rate of a solid fuel in a
fuel direction from a solid fuel injector, wherein a fuel pump is
fluidly coupled to a solid fuel passage disposed axially with
respect to the solid fuel injector and communicatively coupled to
the solid fuel injection controller, wherein the fuel pump is
configured to direct the solid fuel into the solid fuel passage, a
first gas flow rate of a first gas flowing in a first gas direction
from the solid fuel injector through a first gas passage, wherein a
first valve is fluidly coupled to the first gas passage and
communicatively coupled to the solid fuel injection controller, and
a second gas flow rate of a second gas flowing in a second gas
direction from the solid fuel injector through a second gas
passage, wherein a second valve is fluidly coupled to the second
gas passage and communicatively coupled to the solid fuel injection
controller, wherein the first gas passage is disposed
concentrically surrounding the solid fuel passage, and the second
gas passage is disposed concentrically surrounding the first gas
passage, and wherein the solid fuel injector controller is
configured provide the fuel direction axially with respect to the
solid fuel injector by actuating the fuel pump, the solid fuel
injector controller is configured to provide the first gas
direction to concentrically surround the fuel direction by
actuating the first valve, and the solid fuel injector controller
is configured to provide the second gas direction to concentrically
surround the first gas direction by actuating the second valve.
12. The system of claim 11, wherein the solid fuel injection
controller is configured to adjust a ratio between the first and
second gas flow rates to adjust a spray angle of the solid fuel
exiting from the solid fuel injector by adjusting the first valve,
the second valve, or a combination thereof.
13. The system of claim 11, wherein the solid fuel injection
controller is configured to adjust the solid fuel flow rate
relative to the first gas flow rate by adjusting the fuel pump, the
first valve, or a combination thereof, or the second gas flow rate
by adjusting the fuel pump, the second valve, or a combination
thereof, to control breakup of the solid fuel.
14. The system of claim 13, wherein the solid fuel injection
controller is configured to adjust the solid fuel flow rate, the
first gas flow rate, or the second gas flow rate, in response to
feedback from at least component of an integrated gasification
combined cycle (IGCC) system.
15. The system of claim 11, wherein the solid fuel flow rate is a
coal flow rate, the first gas flow rate is a first oxygen flow
rate, and the second gas flow rate is a second oxygen flow rate,
wherein the first gas direction is oriented at a first angle
relative to the fuel direction, the second gas direction is
oriented at a second angle relative to the fuel direction, and the
second angle is at least approximately 5.degree. greater than the
first angle.
16. A method, comprising: controlling a solid fuel flow rate of a
solid fuel traversing a solid fuel passage in an axial fuel
direction from a solid fuel injector by actuating a fuel pump;
controlling a first gas flow rate of a first gas traversing a first
gas passage in a first gas direction from the solid fuel injector,
wherein the first gas direction is oriented at a first angle
relative to the fuel direction by actuating a first valve fluidly
coupled to the first gas passage, wherein the first gas passage is
disposed concentrically surrounding the solid fuel passage; and
controlling a second gas flow rate of a second gas traversing a
second gas passage in a second gas direction from the solid fuel
injector, wherein the second gas direction is oriented at a second
angle relative to the fuel direction by actuating a second valve
fluidly coupled to the second gas passage, wherein the second gas
passage is disposed concentrically surrounding the first gas
passage, and the first and second angles are different from one
another.
17. The method of claim 16, comprising gasifying a spray of the
solid fuel from the solid fuel injector.
18. The method of claim 16, comprising adjusting a first ratio
between the solid fuel flow rate and the first gas flow rate to
control breakup of the solid fuel, and adjusting a second ratio
between the first and second gas flow rates to adjust a spray angle
of the solid fuel exiting from the solid fuel injector.
19. The method of claim 16, comprising varying the solid fuel flow
rate, the first gas flow rate, and the second gas flow rate from a
start up condition to a steady state condition to a shutdown
condition of a gasifier.
Description
BACKGROUND OF THE INVENTION
The subject matter disclosed herein relates to systems and methods
for injecting a feedstock. More specifically, the subject matter
disclosed herein relates to the injection of feedstock for
gasification operations.
Some power plants, for example, integrated gasification combined
cycle (IGCC) power plants, utilize a carbonaceous fuel to produce
energy, typically in the form of electrical power. The carbonaceous
fuel, for example coal, may be processed by a fuel preparation unit
and injected into a gasifier for gasification. Gasification
involves reacting a carbonaceous fuel and oxygen at a very high
temperature to produce syngas, i.e., a fuel containing carbon
monoxide and hydrogen, which burns much more efficiently and
cleaner than the fuel in its original state. The syngas may be fed
into a combustor of a gas turbine of the IGCC power plant and
ignited to power the gas turbine, which may drive a load such as an
electrical generator. Typical gasifier fuel injectors may not
optimally inject the carbonaceous fuel so as to enhance fuel
efficiency and burn characteristics. Accordingly, there is a need
for systems and methods that may enhance efficiency of the
carbonaceous fuel injection into the gasifier.
BRIEF DESCRIPTION OF THE INVENTION
Certain embodiments commensurate in scope with the originally
claimed invention are summarized below. These embodiments are not
intended to limit the scope of the claimed invention, but rather
these embodiments are intended only to provide a brief summary of
possible forms of the invention. Indeed, the invention may
encompass a variety of forms that may be similar to or different
from the embodiments set forth below.
In a first embodiment, a system includes a solid fuel injector. The
solid fuel injector comprises a solid fuel passage, a first gas
passage, and a second gas passage. The solid fuel passage is
configured to inject a solid fuel through a fuel outlet in a fuel
direction. The first gas passage is configured to inject a first
gas through a first gas outlet in a first gas direction. The second
gas passage is configured to inject a second gas through a second
gas outlet in a second gas direction. The first gas direction is
oriented at a first angle relative to the fuel direction. The
second gas direction is oriented at a second angle relative to the
fuel direction, and the first and second angles are different from
one another.
In a second embodiment, a system includes a solid fuel injection
controller and a solid fuel injector. The solid fuel injection
controller is configured to control a solid fuel flow rate of a
solid fuel in a fuel direction from the solid fuel injector, a
first gas flow rate of a first gas in a first gas direction from
the solid fuel injector, and a second gas flow rate of a second gas
in a second gas direction from the solid fuel injector.
In a third embodiment, a method includes controlling a solid fuel
flow rate of a solid fuel in fuel direction from a solid fuel
injector, controlling a first gas flow rate of a first gas in a
first gas direction from the solid fuel injector, and controlling a
second gas flow rate of a second gas in a second gas direction from
the solid fuel injector. The first gas direction is oriented at a
first angle relative to the fuel direction. The second gas
direction is oriented at a second angle relative to the fuel
direction, and the first and second angles are different from one
another.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present
invention will become better understood when the following detailed
description is read with reference to the accompanying drawings in
which like characters represent like parts throughout the drawings,
wherein:
FIG. 1 depicts a block diagram of an embodiment of an integrated
gasification combined cycle (IGCC) power plant, including a
gasifier;
FIG. 2 depicts a schematic view of an embodiment of the gasifier
depicted in FIG. 1;
FIG. 3 depicts a cross-sectional side view of an embodiment of a
gasification fuel injector;
FIG. 4 depicts a simplified cross-sectional view of an embodiment
of the gasification fuel injector as depicted through line 4 of
FIG. 3;
FIG. 5 depicts another simplified cross-sectional view of an
embodiment of the gasification fuel injector; and
FIG. 6 depicts a flowchart of an embodiment of a method for
injecting feedstock and a gas.
DETAILED DESCRIPTION OF THE INVENTION
One or more specific embodiments of the present invention will be
described below. In an effort to provide a concise description of
these embodiments, all features of an actual implementation may not
be described in the specification. It should be appreciated that in
the development of any such actual implementation, as in any
engineering or design project, numerous implementation-specific
decisions must be made to achieve the developers' specific goals,
such as compliance with system-related and business-related
constraints, which may vary from one implementation to another.
Moreover, it should be appreciated that such a development effort
might be complex and time consuming, but would nevertheless be a
routine undertaking of design, fabrication, and manufacture for
those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present
invention, the articles "a," "an," "the," and "said" are intended
to mean that there are one or more of the elements. The terms
"comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
Gasification power plants, such as the IGCC power plant described
in more detail below with respect to FIG. 1, are capable of
gasifying a carbonaceous fuel to produce a syngas. The carbonaceous
fuel, for example coal, may be processed by a fuel preparation unit
and injected into a gasifier by using a fuel injector. Fuel
injector embodiments, described in more detail below, are capable
of more efficiently injecting the fuel by controlling various
properties of a conical spray of feedstock, such as opening angle
and size of the conical spray. The opening angle and size may be
controlled, for example, by using a gasification controller to vary
the flow rate of feedstock and a gas through various fuel and gas
passages included in the fuel injector. The conical spray may be
controlled to realize improvements in gasification performance
and/or to increase the lifespan of IGCC components. Indeed, the
fuel injector embodiments described herein are capable of enhancing
fuel efficiency and burn characteristics of the gasification
process.
With the foregoing in mind, FIG. 1 depicts an embodiment of an IGCC
power plant 100 that may produce and burn a synthetic gas, i.e.,
syngas. Elements of the IGCC power plant 100 may include a fuel
source 102, such as a solid feed, that may be utilized as a source
of energy for the IGCC power plant 100. The fuel source 102 may
include coal, petroleum coke, biomass, wood-based materials,
agricultural wastes, tars, coke oven gas and asphalt, or other
carbon containing items.
The solid fuel of the fuel source 102 may be passed to a feedstock
preparation unit 104. The feedstock preparation unit 104 may, for
example, resize or reshape the fuel source 102 by chopping,
milling, shredding, pulverizing, briquetting, or palletizing the
fuel source 102 to generate feedstock. Additionally, water or other
suitable liquids may be added to the fuel source 102 in the
feedstock preparation unit 104 to create slurry feedstock. In
certain embodiments, no liquid is added to the fuel source, thus
yielding dry feedstock. The feedstock may be conveyed into a
gasifier 106 for use in gasification operations.
In certain embodiments, as described in more detail below with
respect to FIG. 2, the gasifier 106 includes a gasification
controller 107 capable of on-line control of the injection of
feedstock (i.e., fuel) and gas for use in gasification operations.
The gasification controller 107 may control one or more fuel
injectors so as to create a conical spray or spray cone of
feedstock used by the gasifier 106. Characteristics of the conical
spray or spray cone of feedstock such as the size of the spray and
the opening angle of the conical spray or spray cone may be varied
during operations of the gasifier 106, for example, to more
efficiently burn a variety of different fuels and fuel mixtures.
The gasifier 106 may convert the feedstock spray into a syngas,
e.g., a combination of carbon monoxide and hydrogen. This
conversion may be accomplished by subjecting the feedstock to a
controlled amount of any moderator and limited oxygen at elevated
pressures (e.g., from approximately 400 pounds per square inch
gauge (PSIG)-1500 PSIG) and elevated temperatures (e.g.,
approximately 2200.degree. F.-2700.degree. F.), depending on the
type of feedstock used. The heating of the feedstock during a
pyrolysis process may generate a solid (e.g., char) and residue
gases (e.g., carbon monoxide, hydrogen, and nitrogen).
A combustion process may then occur in the gasifier 106. The
combustion may include introducing oxygen to the char and residue
gases. The char and residue gases may react with the oxygen to form
carbon dioxide and carbon monoxide, which provides heat for the
subsequent gasification reactions. The temperatures during the
combustion process may range from approximately 2200.degree. F. to
approximately 2700.degree. F. In addition, steam may be introduced
into the gasifier 106. The gasifier 106 utilizes steam and limited
oxygen to allow some of the feedstock to be burned to produce
carbon monoxide and energy, which may drive a second reaction that
converts further feedstock to hydrogen and additional carbon
dioxide.
In this way, a resultant gas is manufactured by the gasifier 106.
This resultant gas may include approximately 85% of carbon monoxide
and hydrogen in equal proportions, as well as CH.sub.4, HCl, HF,
COS, NH.sub.3, HCN, and H.sub.2S (based on the sulfur content of
the feedstock). This resultant gas may be termed untreated syngas,
since it contains, for example, H.sub.2S. The gasifier 106 may also
generate waste, such as slag 108, which may be a wet ash material.
This slag 108 may be removed from the gasifier 106 and disposed of,
for example, as road base or as another building material. To treat
the untreated syngas, a gas treatment unit 110 may be utilized. In
one embodiment, the gas treatment unit 110 may be a water gas shift
reactor. The gas treatment unit 110 may scrub the untreated syngas
to remove the HCl, HF, COS, HCN, and H.sub.2S from the untreated
syngas, which may include separation of sulfur 111 in a sulfur
processor 112 by, for example, an acid gas removal process in the
sulfur processor 112. Furthermore, the gas treatment unit 110 may
separate salts 113 from the untreated syngas via a water treatment
unit 114 that may utilize water purification techniques to generate
usable salts 113 from the untreated syngas. Subsequently, the gas
from the gas treatment unit 110 may include treated syngas, (e.g.,
the sulfur 111 has been removed from the syngas), with trace
amounts of other chemicals, e.g., NH.sub.3 (ammonia) and CH.sub.4
(methane).
A gas processor 115 may be used to remove additional residual gas
components 116, such as ammonia and methane, as well as methanol or
any residual chemicals from the treated syngas. However, removal of
residual gas components from the treated syngas is optional, since
the treated syngas may be utilized as a fuel even when containing
the residual gas components, e.g., tail gas. At this point, the
treated syngas may include approximately 3% CO, approximately 55%
H.sub.2, and approximately 40% CO.sub.2 and is substantially
stripped of H.sub.2S.
Continuing with the syngas processing, once the CO.sub.2 has been
captured from the syngas, the treated syngas may be then
transmitted to a combustor 140, e.g., a combustion chamber, of a
gas turbine engine 142 as combustible fuel. The IGCC power plant
100 may further include an air separation unit (ASU) 144. The ASU
144 may operate to separate air into component gases by, for
example, distillation techniques. The ASU 144 may separate oxygen
from the air supplied to it from a supplemental air compressor 146,
and the ASU 144 may transfer the separated oxygen to the gasifier
106. Additionally the ASU 144 may transmit separated nitrogen to a
diluent nitrogen (DGAN) compressor 148.
The DGAN compressor 148 may compress the nitrogen received from the
ASU 144 at least to pressure levels equal to those in the combustor
140, so as not to interfere with the proper combustion of the
syngas. Thus, once the DGAN compressor 148 has adequately
compressed the nitrogen to a proper level, the DGAN compressor 148
may transmit the compressed nitrogen to the combustor 140 of the
gas turbine engine 142. The nitrogen may be used as a diluent to
facilitate control of emissions, for example.
As described previously, the compressed nitrogen may be transmitted
from the DGAN compressor 148 to the combustor 140 of the gas
turbine engine 142. The gas turbine engine 142 may include a
turbine 150, a drive shaft 152 and a compressor 154, as well as the
combustor 140. The combustor 140 may receive fuel, such as syngas,
which may be injected under pressure from fuel nozzles. This fuel
may be mixed with compressed air as well as compressed nitrogen
from the DGAN compressor 148, and combusted within combustor 140.
This combustion may create hot pressurized exhaust gases.
The combustor 140 may direct the exhaust gases towards an exhaust
outlet of the turbine 150. As the exhaust gases from the combustor
140 pass through the turbine 150, the exhaust gases force turbine
blades in the turbine 150 to rotate the drive shaft 152 along an
axis of the gas turbine engine 142. As illustrated, the drive shaft
152 is connected to various components of the gas turbine engine
142, including the compressor 154.
The drive shaft 152 may connect the turbine 150 to the compressor
154 to form a rotor. The compressor 154 may include blades coupled
to the drive shaft 152. Thus, rotation of turbine blades in the
turbine 150 may cause the drive shaft 152 connecting the turbine
150 to the compressor 154 to rotate blades within the compressor
154. This rotation of blades in the compressor 154 causes the
compressor 154 to compress air received via an air intake in the
compressor 154. The compressed air may then be fed to the combustor
140 and mixed with fuel and compressed nitrogen to allow for higher
efficiency combustion. Drive shaft 152 may also be connected to
load 156, which may be a stationary load, such as an electrical
generator for producing electrical power, for example, in a power
plant. Indeed, load 156 may be any suitable device that is powered
by the rotational output of the gas turbine engine 142.
The IGCC power plant 100 also may include a steam turbine engine
158 and a heat recovery steam generation (HRSG) system 160. The
steam turbine engine 158 may drive a second load 162. The second
load 162 may also be an electrical generator for generating
electrical power. However, both the first and second loads 156, 162
may be other types of loads capable of being driven by the gas
turbine engine 142 and steam turbine engine 158. In addition,
although the gas turbine engine 142 and steam turbine engine 158
may drive separate loads 156 and 162, as shown in the illustrated
embodiment, the gas turbine engine 142 and steam turbine engine 158
may also be utilized in tandem to drive a single load via a single
shaft. The specific configuration of the steam turbine engine 158,
as well as the gas turbine engine 142, may be
implementation-specific and may include any combination of
sections.
The IGCC power plant 100 may also include the HRSG 160. Heated
exhaust gas from the gas turbine engine 142 may be transported into
the HRSG 160 and used to heat water and produce steam used to power
the steam turbine engine 158. Exhaust from, for example, a
low-pressure section of the steam turbine engine 158 may be
directed into a condenser 164. The condenser 164 may utilize a
cooling tower 168 to exchange heated water for chilled water. The
cooling tower 168 acts to provide cool water to the condenser 164
to aid in condensing the steam transmitted to the condenser 164
from the steam turbine engine 158. Condensate from the condenser
164 may, in turn, be directed into the HRSG 160. Again, exhaust
from the gas turbine engine 142 may also be directed into the HRSG
160 to heat the water from the condenser 164 and produce steam.
In combined cycle power plants such as IGCC power plant 100, hot
exhaust may flow from the gas turbine engine 142 and pass to the
HRSG 160, where it may be used to generate high-pressure,
high-temperature steam. The steam produced by the HRSG 160 may then
be passed through the steam turbine engine 158 for power
generation. In addition, the produced steam may also be supplied to
any other processes where steam may be used, such as to the
gasifier 106. The gas turbine engine 142 generation cycle is often
referred to as the "topping cycle," whereas the steam turbine
engine 158 generation cycle is often referred to as the "bottoming
cycle." By combining these two cycles as illustrated in FIG. 1, the
IGCC power plant 100 may lead to greater efficiencies in both
cycles. In particular, exhaust heat from the topping cycle may be
captured and used to generate steam for use in the bottoming
cycle.
FIG. 2 depicts a schematic view of an embodiment of the gasifier
106 coupled to an embodiment of the gasification controller 107.
More specifically, the gasification controller 107 is
communicatively coupled to a set of valves 170, 172, and a feed
pump 174 for use in fuel injection. The valves 170, 172 may be used
to adjust (e.g., increase or decrease) a gas 176, such as oxygen,
flowing into a gasification fuel injector 178 of the gasifier 106.
Additionally, the feed pump 174 may be used to adjust the flow of
feedstock from the fuel source 102 into the fuel injector 178.
While the depicted embodiment of the gasifier 106 includes a single
gasification fuel injector 178, other embodiments of the gasifier
106 may include a plurality of gasification fuel injectors 178.
As mentioned above with respect to FIG. 1, the gasifier 106 is
utilized to convert feedstock into syngas. In certain embodiments,
the feedstock may be a solid feedstock entrained in a carrier gas
(e.g., nitrogen or CO.sub.2). For example, the solid feedstock may
include coal particles, biomass particles, and other feedstock
particles, entrained in the carrier gas, Consequently, the
gas-entrained feedstock may be caused to flow like a fluid. In
other embodiments, the feedstock may be a slurry feedstock. The
controller 107 may adjust the feed pump 174 so as to redirect the
feedstock from the fuel source 102 into the gasification fuel
injector 178. Additionally, the controller 107 may adjust the
valves 170 and 172, so as to redirect a gas, such as oxygen, into
the gasification fuel injector 178. The gasification fuel injector
178 may subsequently create a spray of the feedstock in a
combustion chamber 180 of the gasifier 106 by combining the flow of
the feedstock with the flow of oxygen, as described in more detail
with respect to FIG. 3 below. The spray is capable of atomizing the
feedstock into a spray cone 182 of feedstock particulate, as
illustrated. The atomizing of the feedstock helps the mixing and
dispersal of fuel and gas in the combustion chamber of the gasifier
106, thereby helping improve gasification. The spray cone 182 of
feedstock particulate includes an opening angle .theta.183. The
opening angle .theta.183 is a two-dimensional vertex angle made by
a cross section through the vertex (i.e., top of the cone) and
center of the base (i.e. bottom) of the three-dimensional cone.
The controller 107 may vary the opening angle .theta.183 and the
size (e.g. height, width) of the spray cone 182 so as to optimally
control the burn characteristics and fuel efficiency of the
gasifier 106. The controller may also optimally control the breakup
and/or dispersal of the fuel. Accordingly, the controller may be
communicatively coupled to a plurality of sensors 184 that are
capable of sensing gasification measurements such as temperature,
pressure, humidity, moderator flow rate, flame characteristics,
spray cone characteristics, and so forth, from various locations
inside and outside of the gasifier 106. Additionally, the
controller 107 may receive other feedback 186 from IGCC plant 100
components such as air separation components, syngas processing
components, sulfur processing components, and so forth.
Consequently, the controller 107 is capable of processing the
sensor 184 information and other feedback 186 so as to efficiently
control the opening angle .theta.183 and/or the spray cone 182
size, as described in more detail with respect to FIG. 3 below.
FIG. 3 is a cross-sectional side view of an embodiment of the
gasification fuel injector 178. In the depicted embodiment, the
gasification fuel injector 178 is a flush-mounted gasification fuel
injector 178. That is, a bottom portion 188 of the gasification
fuel injector 178 is mounted flush with a plane, such as a plane
190, so as to not traverse the plane 190. In the depicted
embodiment, the plane 190 represents a lower surface of the
combustion chamber 180 of the gasifier 106. Consequently, the
gasification fuel injector 178 does not traverse the plane 190 into
the combustion chamber 180. In other embodiments, the gasification
fuel injector 178 may not be flush mounted and may traverse the
plane 190 into the combustion chamber 180 of the gasifier 106.
The gasification fuel injector 178 is capable of injecting a fuel
192 redirected from the fuel source 102 and an oxidation gas, such
as oxygen, into the combustion chamber 180 of the gasifier 106.
Accordingly, the gasification fuel injector 178 includes a fuel
passage 194 and two annular gas passages 196, 198. The fuel passage
194 may be used to inject a flow of the fuel 192, such as the gas
entrained feedstock, outwardly through a fuel outlet 195 into the
gasifier 106. The first annular gas passage 196 may be used to
direct a first flow 200 of oxygen outwardly through a first gas
outlet 197 into the gasifier 106. The second annular gas passage
198 may be used to direct a second flow 202 of oxygen outwardly
through a second gas outlet 199 into the gasifier 106. The outlets
195, 197, and 199 may be disposed in the common plane 190, as
illustrated. By controlling the flow ratio through the two passages
194 and 198, the gasification fuel injector 178 is able to
optimally define the spray cone 182 of feedstock particulate.
Indeed, the gasification fuel injector 178 is capable of defining
any number of spray cone 182 sizes and opening angles .theta.183 as
described below.
The spray cone 182 of feedstock particulate may be created by
combining the injection of feedstock 192 flowing through the fuel
passage 194 with the first gas flow 200 and/or the second gas flow
202 flowing through the two annular gas passages 196, 198 as
follows. The feedstock particulate may be directed to flow in an
axial direction 204 into the combustion chamber 180 of the gasifier
106. The feedstock particulate may then encounter the first and/or
the second gas flows 200, 202. The first gas flow 200 may be
entering the combustion chamber 180 at an angle .alpha.206 relative
to the directional axis 204. The second gas flow 202 may be
entering the combustion chamber 180 at an angle .beta.208 relative
to the directional axis 204. Accordingly, the first gas flow 200
may be represented by a flow vector 210 relative to an axis 212
while the second gas flow 202 may be represented by a flow vector
214 relative to an axis 216. In certain embodiments, such as the
depicted embodiment, the axes 204, 212, and 216, are parallel with
respect to one another. Accordingly, the angle .alpha.206 of the
flow vector 210 is a smaller angle than the angle .beta.208 of the
flow vector 214. In certain embodiments, the angle .alpha.206 may
be between approximately 0.degree. and 70.degree., and the angle
.beta.208 may be between 0.degree. and 5.degree., 15.degree.,
30.degree., 45.degree., or 75.degree.. In certain embodiments, the
angle .beta.208 may be approximately 5.degree. to 75.degree.
greater than the angle .alpha.206.
The first flow of gas 200 represented by the flow vector 210 is
capable of impacting the stream of fuel 192, causing a shear stress
in the stream of fuel 192. The shear stress is capable of atomizing
the stream of fuel 192 into fine particulate matter, creating the
spray cone 182 of particulate matter. Increasing the flow rate
and/or pressure of the first flow of gas 200 will result in
additional shear stress, and thus increase the amount of
atomization of the stream of fuel 192 as well as the height, width,
and opening angle .theta.183 of the spray cone 182. The enlarged
spray cone 182 may thus cause the particles of the fuel 192 to
become more evenly and more widely distributed inside of the
combustion chamber 180. A wider spray cone 180 distribution may be
useful for separating and exposing more of the particles of fuel
192 to gasification reactions. Consequently, better fuel
distribution as well as increased reactions and higher gasification
yields may result. However, creating an overly broad spray cone 182
may result in gasification inefficiencies due to, for example, high
temperatures and/or pressures inside the gasifier 106. Accordingly,
the second flow of gas 202 represented by the flow vector 210 may
be used to reduce and/or refine the spray cone 182.
The second flow of gas 202 is capable of impacting the stream of
fuel 192 at a larger angle .beta.208 than the angle .alpha.206 of
the first flow of gas 200. Additionally, the second flow of gas 202
may exit the fuel injector 178 at the second outlet 199 having a
larger diameter than the first outlet 197 of the first flow of gas
200. In the depicted embodiment, the second outlet 199 is placed so
as to concentrically surround the first outlet 197. Consequently,
the second flow of gas 202 is capable of reducing the opening angle
.theta.183 of the spray cone 182 by causing a circumferential gas
envelope to develop and surround the spray cone 182. The second
flow of gas 202 may envelop the stream of fuel 192 and
circumferentially compress the stream of fuel 192 into a smaller
spray cone 182. The size of the gas envelope may be adjusted by
increasing or decreasing the flow rate and/or pressure of the
second flow of gas 202. Increasing the flow rate and/or pressure of
the second gas flow 202 may result in higher compression that in
turn creates a smaller opening angle .theta.183 of the spray cone
182. Decreasing the flow rate and/or pressure of the second gas
flow 202 may result in lower compression that in turn creates a
larger opening angle .theta.183 of the spray cone 182. Accordingly,
an optimal flow ratio between the flow rate of the first gas
passage 196 and the flow rate of the second gas passage 198 may be
adjusted so as to optimize gasification operations.
A high flow ratio, i.e., higher flow rate through the first gas
passage 196 and lower flow rate through the second gas passage 198,
may result in a broader opening angle .theta.183. A low flow ratio,
i.e., lower flow rate through the first gas passage 196 and higher
flow rate through the second gas passage 198, may result in a
tighter opening angle .theta.183. Reducing the opening angle
.theta.183 of the spray cone 182 may allow for increased lifespan
of gasifier 106 components such as refractory linings, fuel
injectors 178, moderator injectors, and so forth because of the
corresponding reduction in temperatures and pressures experienced
by aforementioned components. Indeed, the gasification controller
107 is capable of closely monitoring gasification data and
controlling the opening angle .theta.183 and size of the spray cone
182 so as to maximize gasification efficiency and minimize
component wear as described below.
The gasification controller 107 may receive a plurality of
measurements, for example, temperature, pressure, humidity,
moderator flow rate, flame characteristics, syngas composition, and
so forth. The gasification controller 107 may then use the
measurements to optimize the spray cone 182, as well as the amount
of fuel 192 being used in gasification operations. For example, if
too little syngas is being produced, then the controller 107 may
add fuel 192 and/or create a broader spray cone 182 by adjusting
the flow ratio of the flow of oxygen through the two gas passages
196, 198. If elevated temperatures and/or pressures are detected in
the gasifier 106, then the controller 107 may reduce the amount of
fuel 192 and/or create a narrower spray cone 182. Indeed, the
controller 107 is capable of efficiently optimizing gasification
operations by controlling fuel rates and by creating any number of
feedstock spray cones 182.
FIG. 4 is a simplified cross-sectional view through line 4 of an
embodiment of the fuel injector 178 of FIG. 3. That is, FIG. 4
depicts a cross-sectional slice through a plane defined by line 4
of FIG. 3, illustrating an embodiment of concentric and/or coaxial
placement of the passages 194, 196, and 198. In the depicted
embodiment, the passages 194, 196, and 198 may be concentrically
and/or coaxially placed around a common axis, such as the axis 204
(shown in FIG. 3) that projects parallel to the z-plane. In other
embodiments, the passages 194, 196, and 198 may not share a common
axis and may be placed off-center with respect to each other. The
fuel passage 194 is a circular fuel passage placed in the center of
the fuel injector 178, as depicted. The first gas passage 196 is an
annular or toroidal (i.e., circular with a hollow center) gas
passage 196 placed to circumferentially surround the fuel passage
194. Accordingly, the first gas passage 196 aids in atomizing the
fuel 192. A circular wall 218 separates the passages 194 and 196.
The second gas passage 198 is also an annular or toroidal gas
passage 198 and is placed to circumferentially surround the first
gas passage 196. Consequently, the second gas passage 198 aids in
creating a gas stream capable of enveloping the atomized fuel 192.
A circular wall 220 separates the passages 196 and 198. An exterior
circular wall 222 separates the second gas passage 198 from the
remainder of the fuel injector 178. In certain embodiments, the
exit outlets 195, 197, and 199 (shown in FIG. 3) corresponding to
the passages 194, 196, and 198 may also include a similar
concentric and/or coaxial arrangement, such that the fuel outlet
197 is placed at the approximate center with the gas outlets 197,
199 concentrically and/or coaxially surrounding the fuel outlet
197.
FIG. 5 is a simplified cross-sectional frontal view of another
embodiment of the fuel injector 178, with the cross-section shown
in the same plane as that of FIG. 4. In the depicted embodiment,
the fuel injector 178 includes a plurality of discrete outlet ports
that may be used as transport conduits and/or outlets for the first
and second gas flows. Accordingly, the first gas flow 200 may be
redirected into the gasifier 108 through a plurality of discrete
outlet ports 224. The discrete outlet ports 224 may be
equidistantly placed so as to circumferentially surround the fuel
passage 195. In the depicted embodiment, each discrete outlet port
224 has the same diameter as each other discrete outlet port 224.
In other embodiments, each discrete outlet port 224 may have a
different diameter from the other discrete outlet ports 224. A
circular wall 226 separates the fuel passage 195 from the discrete
outlet ports 224. The second gas flow 202 may be redirected into
the gasifier 108 through a plurality of discrete outlet ports 228.
The discrete outlet ports 228 may also be equidistantly placed so
as to circumferentially surround the discrete outlet ports 224. In
the depicted embodiment, each discrete outlet port 228 has the same
diameter as each other discrete outlet port 228. In other
embodiments, each discrete outlet port 228 may have a different
diameter from the other discrete outlet ports 228. A circular wall
230 separates the discrete outlet ports 224 from the discrete
outlet ports 228, and an exterior circular wall 232 separates the
discrete outlet ports 228 from the remainder of the fuel injector
178. It is to be understood that while the depicted embodiment
illustrates six discrete outlet ports 224 and twelve discrete
outlet ports 228, other embodiments may have more or less discrete
outlet ports 224, 228.
FIG. 6 is a flowchart of an embodiment of control logic 234 that
may be used, for example, by the gasification controller 107 to
adjust the size and opening angle .theta.183 of the spray cone 182
during gasification operations. Accordingly, each block of the
logic 234 may include machine readable code or computer
instructions that can be executed by the controller 107. The logic
234 may first collect gasification measurements and other feedback
(block 236). As mentioned above, the controller 107 may receive a
plurality of sensor 184 measurements and other feedback 186 from
gasifier 106 activities and from other IGGC plant 100 activities.
The controller 107 may then use the collected data to determine if
it would beneficial to increase the existing opening angle
.theta.183 of the spray cone 182 (decision 238). It may be
beneficial to increase the opening angle .theta.183, for example,
if the gasifier 106 is operating at a lower temperature or at a
lower gasification pressure than desired. Accordingly, the opening
angle .theta.183 of the spray cone 182 may be enlarged by
increasing the flow rate of the first gas flow 200, decreasing the
flow rate of the second gas flow 202, and/or increasing the flow
rate of the feedstock (block 240).
If the controller 107 determines that it would not be beneficial to
increase the existing opening angle .theta.183 of the spray cone
182, the controller may then determine if it may be beneficial to
decrease the existing opening angle .theta.183 of the spray cone
182 (decision 242). It may be beneficial to decrease the existing
opening angle .theta.183 of the spray cone 182, for example, if the
gasifier 106 is operating at a higher temperature or at a higher
gasification pressure than desired. Accordingly, the opening angle
.theta.183 of the spray cone 182 may be reduced by decreasing the
flow rate of the first gas flow 200, increasing the flow rate of
the second gas flow 202, and/or decreasing the flow rate of the
feedstock (block 244).
In certain operating modalities, it may be beneficial to increase
the size of the spray cone 182 while keeping the opening angle
.theta.183 at approximately the same angle. For example, a longer
spray cone 182 may result in an increase in the gasification yield
while keeping the temperature experienced by the refractory lining
proximate to the spray cone 182 to remain at approximately the same
temperature. Similarly, a different fuel having a low heating value
(i.e., a measure of intrinsic energy in the fuel) may benefit from
a longer spray cone 182 in order to more efficiently burn the fuel.
Accordingly, the controller 107 may determine if it would be
beneficial to increase the size of the spray cone 182 while keeping
the opening angle .theta.183 at approximately the same angle
(decision 246). If the controller 107 determines that an enlarged
spray cone would be beneficial; then the controller 107 may
increase the flow rate of the feedstock, increase the flow rate of
the first gas flow, and/or increase the flow rate of the second gas
flow (block 248). The resulting longer spray cone 182 may be at
approximately the same opening angle .theta.183 as the previous
shorter spray cone 182.
In other operating modalities, it may be beneficial to decrease the
size of the spray cone 182 while keeping the opening angle
.theta.183 at approximately the same angle. For example, a
different fuel type may contain a higher heating value and thus may
benefit from a shorter spray cone 182 in order to optimize burn
characteristics of the fuel. Accordingly, the controller 107 may
determine if it would be beneficial to reduce the size of the spray
cone 182 while keeping the opening angle .theta.183 at
approximately the same angle (decision 250). If the controller 107
determines that a reduced spray cone would be beneficial; then the
controller 107 may decrease the flow rate of the feedstock,
decrease the flow rate of the first gas flow 200, and/or decrease
the flow rate of the second gas flow 202 (block 252). The resulting
reduced spray cone 182 may be at approximately the same opening
angle .theta.183 as the previous larger spray cone 182. The
controller 107 may be iteratively determining optimal opening
angles .theta.183 and spray cone 182 sizes. Accordingly, the
depicted embodiment illustrates a return to the collection of
sensor measurements and other feedback (block 236) as the
controller 107 continuously iterates through the logic 234. Indeed,
by iteratively controlling the flow rates of the feedstock and of
the two gases, the controller 107 is capable of creating any number
of spray cones 182 at any number of angles .theta.183. Such
capabilities allow the gasification process to be efficiently
optimized for a wide variety of fuel types, gasifier types, and
gasification operations. Indeed, the controller 107 may be
continuously varying the solid fuel flow rate, the first gas flow
rate, and the second gas flow rate throughout all phases of plant
100 operation, from a plant start up condition to a steady state
condition to a plant shutdown condition of the gasifier 106.
Technical effects of the invention include a fuel injector with a
plurality of fuel and gas passages and a gasification controller
capable of varying the flow rates of the fuel and the gas for
controlling the size and opening angle of a spray cone of
feedstock. The spray cone size and opening angle may be varied so
as to optimally gasify any number of fuel types in any number of
gasification operations. The gasification controller is capable of
on-line control of the size and opening angle of the spray cone of
feedstock. The fuel injector and gasification controller are thus
capable of enhanced flexibility of gasification fuel injection
operations through a wide range of conditions.
This written description uses examples to disclose the invention,
including the best mode, and also to enable any person skilled in
the art to practice the invention, including making and using any
devices or systems and performing any incorporated methods. The
patentable scope of the invention is defined by the claims, and may
include other examples that occur to those skilled in the art. Such
other examples are intended to be within the scope of the claims if
they have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural
elements with insubstantial differences from the literal languages
of the claims.
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